Which game mode in black ops gives the most xp

It really depends on what you are a good at, Search and Destroy gives you 500xp per kill and 1000 bomb related so if you can master Search and Destroy you will be getting mad exp. Demolition is another great one if you don't like Search and Destroy.

Domination is another way to get alot of XP. you get 150 for each position secured, 200 for defending a position or taking someone out who is defending their flag. You also get 50 points per kill. You also get a large bonus if your team wins the round.

Search and destroy will give you tons of XP but if you get killed you must wait until the next round to re-spawn.